Monitoring detectors are used in many fiber-optic components. For example, detectors are typically located in diode laser modules to detect light from the front or rear facets in order to monitor the diode laser's output. They can also be used in fiber amplification systems to detect the optical signals before and after amplification. In still another example, they can be used in monitoring systems to detect the light transmitted through a tunable filter.
Presently, hybrid-integrated optical systems are being manufactured that offer higher levels of integration. For example, in one example, a reference source, tunable filter, and detectors are located in a single hermetic package. In another example, two-stage amplifier modules have been designed. In both of these examples, multiple optical signals are being handled within the same hermetic package.